1. Field of the Invention
The present invention relates to the shaping of sheet material and particularly to severing the corners from sheets of material which have previously been stacked as part of a book manufacturing process. More specifically, the present invention is directed to apparatus for removing the corners of stacked sheets prior to further processing of such sheets in, for example, the course of production of book covers. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
Thin sheets of overlay material are often required in the production of book covers. These overlay sheets must be shaped, specifically the corners must be cut therefrom, prior to use. In the prior art, the sheets of overlay material have been stacked, each stack containing a relatively small number of sheets, and the stacks then manually positioned in a corner-cutting machine. The previously available corner-cutting machines are bench-type appliances which include a supporting surface, with an angled stop, and a manually operable cutting tool. In these known appliances, the four corners of the stacked rectangular overlay sheets are removed, in sequence, through operation of the cutting tool by means of a hand lever.
A corner-cutting appliance of the type generally described above is, for example, disclosed in published German Patent Application Serial No. 36 13 511. This published application describes an appliance having a cutting tool which is in the form of a dish-shaped knife with a cutting edge on the outside of the dish rim. This arrangement, at least in theory, provides a clean and uniform cut.
The withdrawal of partial stacks of overlay sheet material from a larger stack, the placing of such partial stacks on the supporting surface of a corner-cutting appliance, the alignment of the stack in the appliance and the subsequent cutting operation is an extremely time-consuming, labor-intensive operation. This operation occupies a substantial portion of the time available to a machine operator who may have other tasks to perform. Also, because the corner-cutting operation has previously been performed manually and misalignment of the stack of sheets which are to have their corners removed is thus an inherent possibility, great care has been required in the interest of minimizing cutting inaccuracies with the resultant waste of material.